Db-Thalassemia Patients With Homozygous Xmn-1 Polymorphism That Are Characterized By A Milder Phenotype

Abstract

Thalassemia intermedia is an inherited group of disorders with clinical presentations varying between the thalassemia carrier state and thalassemia major phenotype. This variability depends on the heterogeneous molecular mechanism of the disease. db-Thalassemia is a heterogeneous disorder characterized by elevated levels of Hb F in adult life. It is a rare disorder in Pakistan. The homozygous variety g (g db) are rare , present with a wide range of clinical phenotypes, and belong to the group of thalassemia intermedia. We determined clinical, haematological and genetic features of Inv/Del Gg (Agdb) o db in 100 thalassemia intermedia patients, six of which had Inv/Del Gg (Agdb) o mutations, all were homozygous (+/+) for Xmn-1 polymorphism. Among pathological features, high levels of hemoglobin F, late clinical presentation, hepatosplenomegaly, variable transfusion dependence and an absence of alpha chain deletions were observed. This study explains strong link between the Xmn-1 Gg-polymorphism and the Asian-Indian Inv/Del. These findings explain the determined capacity of patients to produce fetal hemoglobin in delta beta-thalassemia. These patients lack alpha chain deletions and may potentiate the qualification of factors favouring HbF production as a prominent source of the thalassemia intermedia phenotype.